Control system



June 6, 1933. A. LfMoREAu 1,912,909

CONTROL SYSTEM Filed Feb. 19, 1927 6 Sheets-Sheet 1 WITNESSES: INVENTOR AT'II'ORNIEY June '6, 1933.

A. L. MORE-AU CONTROL SYSTEM Filed Feb. 19. 1927 6 Sheets-Sheet 2 I A/berf Moreau ATTORNEY June 6, 1933. A. MOREAU 1,912,909

CONTROL SYSTEM Filed Feb. 19. 1927 6 Sheets-Sheet 3 INVENTOR AZEIORNEY A/De'rf' L. Moreau Ill-M flm Lwlww m Em 4 6R mmmw m vow mom WITNESSES Z June 6, 1933. A. L. MOREAU 1,912,909

CONTROL SYSTEM Filed Feb. 19. 1927 6 Sheets-Sheet 4 w WITNESSES: INVENTOR 4 M A/berf L Moreau i} A'i'TORNEY A. L. MOREAU CONTROL SYSTEM Filed Feb.

June 6,- 1933.

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INVENTOR A/berf L. Moreau ATTRNEY A. L. MOREAU CONTROL SYSTEM June 6, 1933.

Filed Feb. 19.

1927 6 Sheets-Sheet 6 ommm I I 3 TQ MN 0 Q b no INVENTOR A/berf L Mareau WITNESSES: I /4,! W

AhoRnEY I Patented June 6, 1933 van s STATES PATENT oFFicE ALBERT L. MOREAU, 0F WILKINSBURG, PENNSYLVANIA, ASSIGNOR TO WESTINGHG'USE- ELECTRIC & MANUFACTURING COMPANY, A COREORATION- O-F PENNSYLVANIA CONTROL SYSTEM Application mes February 19, 1927. Serial No. 169,504.

My invention relates to signalling systems and more particularly tothat class known as supervisory control systems.

An object of my invention is'to provide circuits.

Another" object of my invention is to provide means for synchronously switching a signal line connecting two stations from unit to unit at one end and from key to key at the remote end, and for checkingeach point before completing the selective circuit.

Another object of my invention is to pro- I vide means for checking or identifying each selecting point in a supervisory control system wherein the apparatus units are connected to signalling lines in synchronism with the connection of their indivldual units to said signalling llnes.

Another object of my invention is to provide means forautomatlcally stopping further operation of the system when it falls out of synchronism, and for manually restoring the set to its normal position; I

Another ob ect of my invention is to provide means for manually restoring the selectlng apparatus to its normal position by a single operation;

Another ob ect of my invention is to provide code means for operatinga synchronous relay supervisory control system.

Another object ofmy invention is to provide means including circuits for synchronously operating chains of .relays at two remote points by an enforced sequence so that no operation can be performed until a pre determined precedim operation has been performed.

Another object of my inventionis to provide means for operating a synchronous relay supervisory control system with very simple circuits, a minimum number of relays, all of said relays being of one standard selected unit or circuit connected to the signalling line connecting the stations after such correct identification.

There are other objects of my invention Which,together with the foregoing, will appear in the specification whichxfollows.

I In generahmy invention comprises a synin which eachof the circuits as it is selected at each endis first identified or checked before being connected to the signalling line connecting the stations. A non-synchronous selectlon prevents the check circuit from operatmg and stops the selecting apparatus which is thereupon restored to itsnormal position at'both ends of the system. v 7

Referring now to the drawings, Figs. 1 and 2 are diagrams disclosing the preferred embodiment of the apparatus and circuits at the dis'patchers end and Figs. 3 and 4 are diagrams disclosing the apparatus and circuits at the substation.

Figs. 5 and 6' are charts showing the'rela- .tion of therelay operations during a selecting cycle and a non-synchronous cycle.

Referring more particularly to Fig. 1, the

relays 161 to 17 0 are the selecting relays in-. dividual to the point equipment at thev oflice and are arranged to energize and dc-energize sequentially to connect their individual apparatus .units to the signalling line. By point equipment is meant broadly any apparatus units at the selected positions. Switchover relays 101 to 110 are individual to the selecting relays and energize sequentially. Each switchover relay operates as a result of the energization of its individual selecting relay and functions to transfer the selecting relay energizing circuit from its own selecting relay to'that of the succeeding selecting relay while, at the same time, opening'the original energizing circuit of its own individual selecting relay. I v

The key 137 is an individual operating key. It is provided with a cam-shaped twisting handle 14:3 pivoted at 142 about which it may rotate to a vertical position fromits'disclosed horizontal position to permitthecontactors 14A; and 145 to close their inner contacts. A stop key, such as 136, is

chronous-relay supervisory control system arranged in a circuit to stop the selecting action at any desired point by the opening of its contacts. Lamps 135 and 138 are individual to each point for indicating the two possible conditions of a circuit breaker, tripped or closed. It is understood, of course, that this point equipment is individual to each apparatus unit to be selected. Additional stop keys 1 17, 1 19, etc., are disclosed.

Although only ten selecting relays and their individual switchover relays are shown it is obvious that any number desired could be employed, depending upon the number of apparatus units in the system. The relay 158 is controlled by the position of each of the individual equipments consecutively for switching the line 288 connected to the supervisory line 289 to receive a changed supervisory signal.

Relays 156 and 157 operate in response to received supervisory'signals for repeating the signal to the individual equipment. Relay 160 is arranged to be energized following a failure or non-synchronous operation for removing ground from the normal holding circuits and restoring the apparatus to normal. The relay 159 energizes following the restoration of all individual equipment upon such a failure to, in turn, de-energize the relay 160 which is thus restored to its original condition.

Referring to Figs. 2 and 3, the relays 22 1 and 335 are the normal holding relays connected in a series circuit over the supervisory conductor 289 and are arranged to be deenergized when a start key is closed at the ofiice end or in response to an automatic operation at the substation end.

The start relay 225 is connected in a prepared circuit over the front armature contact of the normal holding relay 224 to the start key 204 which, when closed, will energize this relay. The conductor 198 is normally grounded over the back armature of the synchronous restoring relays 160 and 159 so that the relay 225, when energized by the closing of the start key, locks up over one of its armatures and the conductor 198.

The relay 229 is energized over a front contact armature of the starting relay 225 and the conductor 198 and switches the supervisory line 289 from its normal holding circuit, including the relay 224 at the office and relay 335 at the substation to its operating position over the front contact while simultaneously switching the control line 290 from its normal open position to its operat in position over the front contact of its armature.

The normal holding relay 335 is energized in series with the relay 224 and is so arranged when it is de-energized as to com station in a similar manner to the operation of relay 229 at the office, switches the normal holding circuit over the control line 290 to its operating position over the front contact of one of its armatures, while simultaneously switching the supervisory line 289 to its operating position. 7

The relay 306 is energized by the relay 301 simultaneously with the switching of the control and supervisory lines to their operating positions, thus closing the first drive circuit. The relay 336 at the substation and the relay 258 at the ofiice are energized in a series circuit over the drive line 291 and function to completeenergizing circuits for the individual selecting relays. These cir cuits for the selecting relays are sequentially completed for the selecting relays by the switchover relays 101 to 110, as has already been mentioned and as will be described in more detail hereinafter. 7

The relay 257 is arranged to energize simultaneously with each of the selecting relays 161 to 170 to, in turn, energize the cut-off relay 256. This relay, upon energization, opens the original energizing circuit of the selecting relay such as 161 so as to prevent the energization of the succeeding selecting relay, such as 162, when a switchover relay, such as 101, is energized for transferring the succeeding impulse. Similarl at the substation end, the drive line relay 336, upon energization, completes an energizing circuit for the selecting relays 112 to 121, the particular selecting relay to be energized depending upon the position of the switchover relays 401 to 410, as has already been described and which will be de scribed in more detail hereinafter.

The relay 337 is energized simultaneously with each selecting relay to, in turn, energize the final cut-off relay 338 which, upon energization, cuts off the impulse to the selecting relay to prevent the succeeding selecting relay from being energized when a switchover relay, such as 401, is energized.

The check relays 263 and 305 are energized in series over either the conductor 289 or the conductor 290, depending upon the particular selecting relays which are energized and through the contacts of the selecting relays. The circuit for energizing these two relays inseries is dependent upon the correct energization of the equivalent selecting relays at both ends of the lines and this circuit constitutes the check or identifying selecting circuit.

Each check circuit of a point equipment is distinguished from all the others by the polarity or line over which the impulse is transmitted. Unless this check circuit functions properly, these checking relays 263 and 305 will not energize and, as will be described in more detail hereinafter, the selectors will stop functioning. This iden- I relays from energization; I

'Atthe same time, the relay 261 energizesto automatically operate the restoring relays 159 and 160. The relay 339 at'tlieflsubstation is energized if the check circuit'fails to opcrate to energize the restoring relays 340 and tification of'eacli selecting point has proved to be of considerable importance in system in. which accuracy, as in this case, is a necessary feature.

The relay 262 is energized over the front contact of an armature of the check relay 263 to, in turn, complete a circuit for ,check circuit cut-off relay 228. The 'checkcircuit cut-oli relay 228 is arranged to energize after the check circuit has been com pletcdfto open the check circuit and prepare the control and supervisory lines 290 and 289 to be switched to their final operating positions; Following this'preparation, the relay 227. is energized tofinally complete the prepared selecting ClICllltS tllIOllgll the control and supervisory lines.

I The relayl3 l2 energizes over a front contact of one of the a-rinatures ofthe check relay 305 and, in turn, completes an energizing circuit for tlie"-check circu1t cut-oil relay 302 which, cuts'off the check circuit at the substation and switches the control and superv sory lines to a prepared circuit for connection o the selected point. The relay ble in the s stem and'the rela 264 at the Y 7 oflice is energized to open onepoint in'the circuit of the check relays to prevent these Following the switching over of the control and supervisory lines to their selecting circuits the relay 259 is energized and prepares a circuit for the relay 260 which is controlled by each stop key. With the stop key in an open position, the relay 260 is not energized and the stepping operations stop, but, ifthe stop key is in a closed position, the relay 260 is energizedto open the drive circuit at armature 275, as will be explained in more detail hereinafter, and the, appara- L tus is restoredto normal nre' arator for a second operation.

The relays 222 and 307 function to reverse the polarity of the impulses on the drive line and are controlled by the relays 221 and 308 respectively which, in turn, are controlled by the particular selecting relays en ergized as will be described in more detail hereinafter. I I

The relays 220 and 309 are energized by particularvenergized selecting relays -1I1 an energized position to restore therelays 221 r and 222 to their normal position. The relay 265' would be energized if any selecting re- 7 lay should stick up at a time when itnorv. nallyshould have dropped out and, in turn,

energizes the relay 264 to open the'check circuit. The key 209is arranged to manually control the drive circuit, giving the-dis patcher manual control for releasing the se lecting apparatus to normal, irrespective of;

position of theselec'ting rethe particular lays.

- In order the invention may be better understood, a detailed description of: the op-- ,erations which take place fo'llowingan auto-o matic operation of a circuit breaker,;and a manual operation by the dispatcher in clo sing hisstart key and operating one of the individual keys, will now be given. The chart shown in Figure 5 shows'thecondit'ion of the various. relaysduring the cycle of 1 operation to be described. Inaddition the relays in the "circuit diagrams are-provided with numbers 1 enclosed in a circle. The

number indicates. the unit-oftime'when the relay operates as compared to other-operations; Thus the'firstrelay to energize was chosen as period 1. The next'e nergi'zed're- 1 lay therefore operates in periodj2.- A dash beneathlthe circle indicates a de-energization.

- Normally a holding 1 circuit is completed for the relays 224 at the office and 335 at the substation from ground atthe oflice over armature 239 and its back contact, through winding of the relay 224, back contact and armature'295, supervisory conductor 289,'ar

mature: 312' and its back contact, through and armature 326and' battery to' ground.

This circuit, it will be -noted, is completed .over armature contacts of'the relays 229 at the ofiice and 301 at the substation. These two relaysare arranged to be energized. im-

.mediately following the opening of this holding circuit from either end of the line for switching the: lines to their operating positions. I

This holding circuit, it willbe noted, is also completed/over the armatures of, relays 'the windingof therelay 335, back contact m5 223 at the office and 306 at the substation. V

The relay 223, as will appear shortly, is directlylcontrolled over an armature of the relay 229 whichis arranged to. be not only ole-energized by opening of the holding circuit but also in response to a manual operation by closing the start key 204 at the oflice. Thus, a closing of the start key 2041 at the ofiice not only results in the .energization of the relay 229, therebyopening the.

holding circuit, but also in the energizationv of the relay 223 to "further open the holding circuit and to place ground upon the cone ductor 183 which, as'willrbe described shortcontrols the connection of battery to the holding circuit, is directly controlled by'the relay 301 which, in turn, may be energized either by the opening of the holding circuit orby the automatic operatlon of a clrcuit breaker, this latter operation energizing the i T pletes relay 334 to complete an energizing circuit for the relay 301.

Referring again to the energization of the relay 224 over the holding circuit, it Will be noted that an energizing circuit is prepared for the relay 225 over the front contact of armature 241, and that an ener izing circuit is completed for the lamp 202 over a circuit from ground in Fig. 1, armature 17 5 and its back contact, armaturel77 and its back contact, conductor 198, armature 242 and its front contact conductor 183, through the lamp 202, conductor 184 back contact and armature 240, armature 238 and its back contact and battery to ground.

The illumination of lamp 202 indicates that the set is in its normal resting position. In order to start the set into operation, the dispatcher closes the start key204 and a circuit is completed for the manual starting relay 225 from ground over the key 20 4, conductor 181 front contact and armature 241, through the Winding of the relay 225 and battery to ground.

The energization of the relay 225 coma locking circuit for itself from ground over the conductor 198 traced above, the front contact and armature 244, and through the Winding of relay 225 to battery and ground, While at armature 243, ground from conductor 198, is extended from the front contact and armature 244 through the armature 243 and its front contact to the.

Winding of relay 229 and battery.

The relay 229 is energized and switches the control and supervisory lines 290 and 289 from their normal non-operating position to their operating position over armatures 255 and 295 and their front contacts,

' respectively.

As a result of the armature 295 moving from its back to its front contact, the holding circuit for the relay 224 at the office and the relay atthe substation previously traced is o ened and these rela s are deenergized.

The de-energization of the relay 224 at the office opens the circuit for the lamp 202 at the front contact of armature 242, and,-

gized as long as there is ground on conductor 198, and the holding circuit is not completed.

Since the holding circuit can no longer be completed unless relay 229 is ole-energized, the relay 229 can only be tie-energized now by removing ground from conductor 198. The significance of this feature will appear in the description Which is to follow.

A further result of the de-energization of the relay 224 is to open the prepared starting circuit for the relay 225 at armature 241.

The energization of the relay 229 not only opens the original holding circuit for the relay 224 but also completes the, energizing circuit for the relay 223 from ground through battery, Winding of relay 223, front contact and armature 254, back contact and armature 242, to ground o-ver conductor 198. The energization of the relay 223 opens a further point. in the normal holding circuit of the relay 224 at armature 239, transferring the ground at this point to the conductor 190, thus preparing locking circuits for all the switchover relays 101 to 110. By this arrangement, the switchover relays 101 to 110 are not provided With locking circuits during the normal nonoperating condition of the system, and Will therefore not lock up should any one of them acci- V dentally energize momentarily.

At armature 240, a further point in the energizing circuit of the lamp 202 is opened at the back contact of the armature, and a circuit is completed for the lamp 205 from ground over the back contact and armature 237, conductor 179, through lamp 205, conductor 180 front contact and armature 240, armature 238 and its back contact andbat tery to ground. The illumination of the lamp 205 indicates to the dispatcherthatthe set is noW in operation.

At the substation, the opening of the holding circuit by the energization of the relay 229 ale-energizes the relay 335. The de-energization of the relay 335 opens the prepared circuit for the automatic starting relay 334 at armature 349 and completes an energizing circuit for the switchover relay 301- at armature 348 and its front contact, over a circuit from ground through battery, Winding of relay 301, back contact and armature 348, back contact and armature 359 and back contact and armature 361 to ground.

The energization of the relay 301 switches the holding circuit of the supervisory conductor 289 from the back contact of armature 312 to its operating position over the front contact of armature 312 and closes an operating circuit for the control line over the front contact of armature 311.

The energization of the relay 301 also completes an energizing circuit for the relay 306 from ground through battery, Winding of the relay 306, front contact and armature 310 to ground over the conductor 399.

The energization of the relays 229 and 301 follow the starting operations and function to switch the control and supervisory lines to their operating positions.

The drive circuit, which has heretofore been held open, may now, therefore, be

closed, and relay 306 is, therefore, directly controlled by the energization of the relay 301 to complete the drive circuit while, at the same time, opening a further point-in the original holding circuit at armature 326 to completethe drive circuit at armature 325. At the same time, the energization; of the relay 306 places ground upon. conductor 366 to prepare locking circuits for all the switchover relays 401 to 410. Here again, it will be noted, the switchover relays have no locking circuits during the normal nonoperating period of the system; 7 V The first drive circuit is now completed from ground at the office through battery, the back contact and armature 238 of the battery reversal relay 22 2, armature 240 and its front contact of the disp'atchers start relay 223 through the winding'of the drive relay 258, one contact 210 of the restoring key 209, the'back contact and armature 275 of the line cut-off relay 260, the contact 215 of the restoring key 209, contact 216 of the key 213 over the drive line 291 to the winding of the drive relay 336 at the substation, front contact and armature 325 of the substation start relay306 and armature328 and its back contact of the switchover relay 307 to ground 7 V I I The energization of the relay 258 at the office completes an obvious energizing circuit for the relay 257. Simultaneously with the energization of the relay 257', anenergiz- I p thus by-passlng the armature 354 and being dependent solely upon the condition of the ing circuit is completed for the first selecting relay from ground over armature 272 and its front contact, armature 267 and its back contact, over theconductor 189, armature 112 andits back contact, andthrough the winding of relay 161' to battery and ground. v

The energization of the relay 161' com.- pletes a locking circuit for itself from ground through battery, winding of relay 161, first contact of the relay 161, over the conductor 193, and front contact and armature 272 to ground. The locking circuit for the selecting relay 161, it will be noted, by-

passes the armature 267 and is dependent solely upon the energized condition of the drive relay 258. 1...

The relay 257 and the selectingrelay 161 are thus'energized simultaneously over multiple circuits, each of the relays obtaining ground over armature 272 and its front contact. As a result of the energization of the relay 257, an energizing circuit is completed for the relay 256 from ground through bate tery, .winding of relay 256, front conta'ct and armature 270 and front contact and armature 272 to ground.

The energizationof the relay 256 opens the originally traced energizing circuit for theselecting relay 161 at armature 267. It will be'noted, however, that the relays 257 and 161 are energized simultaneously and that the opening of the energizing circuit for the selecting relay 161 did not occur until the relay 256 was energized, following the energization of the relay 257. The energization'of the relay 256 is intended-to open the original energizing circuit for the selecting relay so that, when the switchover relay 101, the operation of which is about tobe described, is energized and switches the selecting impulse'circuit of the drive relay from the first to the second selecting relay, it will be opened at armature 267 and, therefore, only one selecting relay can be energized by a single drive impulse. At the substation, the energization of the relay 336 completes an obvious energizing circuit for the relay 337 over the armature 350 and its front contact and, simultaneously with the energization of the relay 337, completes'an energizing circuit for the selecting relay 412 from ground over armature 350 and itsfront contact, armature 354 and its back contact, conductor 367 armature 447 and-its back contact,'throu'gh the winding of selecting relay 412 and battery to ground. The relay 412 and relay 337 are thus energized simultaneously.

The energization of relay 412 completes a locking circuit for itself from ground through battery, Winding of relay 412 and its frontcontact, the conductor 374 and the front contact and armature 350 to ground,

drive relay336. V I

The energization of the relay 337 completes an energizing circuit for the relay 338 at armature 352 and its front contact, and armature 350' and its front contact. The energization of the relay 338 opens the original-energizing circuit of the selecting relay, thereby preventing further energization of any selecting relay at this time following the energization of the switchover relay. I A further result ofthe energization of relay 338 is to prepare an energizing circuit for the restoring relay 339 shouldthe set be v in a non-synchronous condition. I

Immediately following the energization of the selecting relays-161 and412, and simultaneously with the'energization of the r elays 256 at the office and 338 at the substation, a checking circuit, for identifying which of the pa'rticular'sele'cting relay has been energized, is completed from ground at the ofiice'to the fourth contact of the firstv selecting relay 161, conductor 195,back con tact and armature 28 3,thecontac't 214 of the n TU restoring key 209, through the winding of the check relay 263, armature 247 and its back contact, back contact and armature 253, front contact and armature 255, conductor 290, armature 311 and its front contact, armature 314 and its back contact, back contact and armature 321 through the winding of the check relay 305, conductor 379, armature 471 and its back contact, through the fourth contact of the selecting relay 412, the back contact and armature 472 and through the winding of relay 422 and battery to ground.

This check circuit, it Will be noted, is completed through a contact of each of the se-. lecting relays in energized condition and through an armature contact of relay 264 which, as will be described hereinafter, functions in case the checking circuit fails to operate to thereupon instantly open the checking circuit and prevent it from opera tion.

The checking circuit is also completed through the contacts of the key 209 so that, should the dispatcher desire at any time to restore the apparatus to normal, he need only to operate the key 209 to open the check circuit. When the time comes for the check circuit to operate, it will thereupon fail, and the restoring will take place in a manner to be described.

At the substation, a circuit is completed through the armature contacts of the restoring relay 423 which function upon a nonsynchronous condition to restore the apparatus while holding the check circuit open.

The check circuit is completed, as has been already noted, instantly following the energization of the selecting relays and, should the check circuit, for any reason, fail to operate immediately, its circuit would be circuit for the switchover relay 101 from ground through battery, winding of the relay 101, through the third contact of the selecting relay 161, conductor 194, front contact and armature 268 and front contact and armature 273 to ground.

The energization of the switchover relay 101 completes a locking circuit for itself from ground through battery, winding of the relay 101, front contact and armature 111, conductor 190, front contact and armature 239 to ground and at armature 112 transfers the impulse from the drive relay which is completed over conductor 189 to the second selecting relay 162 over armature 112 and its front contact, and a rma ture 114 and its back contact. This circuit however is not completed at this time because 1t is opened at armature 267, as has already been descrlbed.

t the substation, the energization of the relay 412 completes an energizing circuit for the switchover relay 401 from ground to battery through the Winding of relay 401, thirdcontact of the selecting relay 412, conductor 375, the front contact and armature from ground through battery, winding of the relay 401, front contact and armature 446, conductor 366. and the front contact and armature 324 to ground and transfers the energizing circuit from the drive relay 336, and conductor 367, to the second selecting relay 413 over armature 447 and its front contact, and armature 449 and its back contact. This circuit, however, is not completed at this time, since it is opened at armature 354, as has already been explained.

Referring again to the check operation, the energization of the relay 263 at the office completes an obvious energizing circuit for the relay 262 which, in turn, completes a locking circuit for itself over armature 278 and its front contact and armature 273 of the drive relay 258 to ground.

The energization of the relay 262 also completes an energizing circuit for the relay 228 from ground through battery, winding of the relay 228, front contact and armature 279 to ground over the front contact and armature 273.

Since the energization of the relay 262 is directly dependent upon the energization of the check relay 263, its energization occurs only after the check circuit is com pleted, indicating thereby that the correct selection has been made.

Since the check circuit has correctly operated, the control and supervisory lines are swltched to their indivldual selection points. The relay 228 IS, therefore, energlzed over the front contact of the relay 262, as has already been described which switches the control and supervlsory line preparatory "to the final switching to be performed by the for the check lamp 203, which indicates to the dispatcher that synchronous operation of the corresponding selecting relays at the office and substation has been obtained. The

energizing circuit for the check lamp cX- tends from ground,front contact and armature 273, back contact and armature 285, back contact and armature 281, front contact and armature 251, conductor 182, and lamp 203 to ground. A further result of the energization of the relay 228 is to, complete an energizing circuit for the relay 227, from ground through battery, winding of the relay 227 front contact and armature 251, back contact and armature 281, the.

' At the substation, upon the original ener-- gization of the check relay 305, an energizing circuit is completed for the relay 342 from ground over armature 323 and its front contact and through the Winding of the relay 342 to battery and ground;

The energization of the relay 342 completes a locking circuit for itself from ground through battery, windingof the .relay 3412, front contact and armature'363, and

the front contact and armature 350 to ground and completes an energizing circuit for the relay 302 from ground through battery, winding of the relay 302, front contact and armature 362 and the front contact and armature 350 to ground.

As in the case of the ofiice, the energization of the checking relay 305 is evidence that the correct selecting relays have been energized at the office and at the substation and that, therefore, the control and supervisory lines may be switched totheir individual selecting circuits. The relay 342 is thereupon energized to, [in turn, energize the relay 302, as has already'been described. The relay 342 must be arranged to" 0p erate intermediate the check relay 305 and the switchover relay 302, owing to the fact that one of the functions of the relay 302is to open the check circuit and, therefore, this relay could not be directly controlled by the check relay but rather by the relay 342 which, by lockin up, gives the relay 302 siifiicient time to be completely energized.

The energization of the relay 302 switches over the control and supervisory lines preparatory to the'fi'nal switching operation and, at the same timc',.opens the original check circuitof the relay" 305 at armature 3141. f i

A further result of the energization of the relay 302 and the derenergization of the check relay 305 is to complete an energizing circuit for the finalswitchoverrelay303 from ground through battery, winding of the relay 303, front contact and armature 313, back-contact and armature 322, conductor 380, back contact and armature 173, conductor 381, and front contact and armature 351 to ground.

Withthe energization of the relay 303 at 0 the substationand 227 at the office, the con-- trol and'supervisory lines are switched to their selecting circuits.

From the foregoing,it will be noted that the drive impulse functions to first energize the individual selectingrelays' at each end. Each of these selecting relays, in turn, locks itself over circuits including the front armature contacts of the drive relays While, at the same time, the original energizing curcuits are opened. V

The selecting relays, upon energization,

complete a check circuit which energizes the relays for switching the control and su' pervisory lines, normally disconnected from the selecting circuits to these circuits and, therefore, to the individual equipment.

In'the meanwhile, the energization of the selecting relays -completes energizing circuits for their individual switchover relays, preparing a circuit, therefore, for the succeecling selecting relays.'

The drive line is now closed, andthe supervisory and control lines are in'position for connecting the first apparatus unit at. .the substation to its individual operating keys and supervisory lamps at the ofiice.

Oneof the results-of the'energizati'on of relay 227, in addition to finally switching the control and supervisory lines to their operating selectingpositions, is tocomplete an energizing circuit for the relay 259 from ground through battery, armature-250 and its front'contact winding of the relay 259,

front contact and armature 278, and the front contact and armature 273 to ground.

The energization' ofthe relay 259 over the above circuit prepares a circuit for'the relay 260. The selecting circuits for the first'point having been completed upon the ene'rgization of the relay 227, it is evident that preparations may now be made for starting a second cycle of operations similar 'to the above traced operations for energizing the second selecting'relays at the sta tlon. 'The energization of the relay 259 operates in response to the final selection for preparing an energizing circuit for the relay 7 260 which, in turn, depends upon the posi-- tion of the stop; key forcompletion of this circuit.

In order to describea complete cycle of operations, it will be assumed, for the presout, that the stop. key 136, individual to the first selecting point, has not been opened. A'circuit is thereupon completed. for the relay 260 from ground throughibattery, wind-v ing of the relay 260, front contactand armature 12741, conductor 185, through the contact-s of the stop key 136, and the second contacts of the selecting relay 161 to ground.

The energization of the relay 260 C0111- pletes a locking circuit for itself, by passing the armature 274 over the front contact and armature 276 and, at armature 275, opens the drive circuit.

Opening the drive circuit at armature 275 de-energizes the relays 258 at the ofiice and 336 at the substation.' The de-energization of the relay 258 opens the energizing circuit for the relays 256 and 257 at armature 272, and these relays are tie-energized.

The locking circuit for the selecting relay 161 is also opened at this time, and the selecting relay is tie-energized. The relays 259, 262 and 228, which are energized over the front contact of armature 273, are now de-energized.

The de-energization of the relay 228 opens the energizing circuit for the relay 227 at the armature 251. The de-energization of the selecting relay 161 opens the energizing circuit for the relay 260, and the drive line is again closed to start the second cycle of operations.

At the substation, the deenergization of relay 336 opens the energizing circuit of relays 337, 338, 342, 412, 303 and 302 at armature 350. The de-energization of relay 302 opens the energizing circuit of relay 303 at armature 313. The apparatus, it will be noted, is now in exactly the same condition it was in when the start operations were complete in preparation for the first selecting cycle except that switchover relay 101 is energized.

The operations which have been described in detail will now be repeated, the only exception being that, upon the second energization of the drive relay 258 at the ofiice, the selecting impulse is transmitted from ground over the armature 272 and its front contact and armature 267 and its back contact, the conductor 189, through the armature 112 and its front contact and armature 114 and its back contact tothe winding of the second selecting relay 162. This is due to the fact that the first switchover relay 101, having been energized, has remained locked in its energized position and, therefore, switches the impulse from he drive relay to the second selector relay.

In a similar manner, the second switchover relay 102 will now be energized to switch the third impulse from the drive relay over armature 114 and its front contact to the third selectins relay/ 163 over arnia ture 116 and its back contact. In this manner, the individual equipment at the office is sequentially connected to the control and supervisory line while its associated apparatus units atthe substation are simultaneously connected to the control line in synchronism therewith. The check operation described in detail for the first selection functions for each selection, although different check circuits, as described hereinafter, are completed for each selection.

In order to illustrate the manner in which the dispatcher may operate the selected unit, it will be assumed that the stopkey 136 was pulled out, that is, the contacts were open. Upon the closing of the start key'204, the cycle of operations, as described in detail above, will occur up to the point at which an energizing circuit is prepared for the relay 260. This circuit, however, is not completed, owing to the fact that the stop key, as has been noted above, is in an open position. The drive relay 258 will, therefore,

remain energized, and all the apparatus will remain in its operated condition.

The dispatcher, in order to close the circuit breaker 431 which is now shown in the tripped position, will operate its individual control key 137 by rotating the cam 143 about its pivot 142 to permit the contacts 144 and 145 to close their inner contact plates. The dispatcher will also close the contacts of the master key 206. V

A circuit will thereupon be completed from ground over the right hand contact of the master key 206, the inner contact 145 of the key 137, the last contact of the sclecting relay 161, conductor 197, armature 249 and its front contact, front contact and armature 253, front contact and armature 255, control conductor 290, armature 311 and its front contact, armature 314 and its front contact, front contact and armature 316, the conductor 378 through the seventh contact of the selecting relay 412, the armature 438 and its front contact and through the winding of relay 428 to battery and ground.

The energization of the relay 428 completes an energizing circuit for interposing relay 430 over the armature 443 which, in turn, completes an energizing circuit for the closing solenoid 432. The circuit breaker is thus closed.

As the circuit breaker moves from its tripped to its closed position, the energizing circuits for the relays 425 and 426 are opened. The relay 425 is a slow-release relay and maintains a circuit for the relay 424 for an interval after the pallet contacts are opened. The de-energization of the relay 425 opens the energizing circuit for the relay 424.

After an interval of time, sufiicient to permit the circuit breaker to latch in its closed position; the slow-releaserelay 424 de-energizes, and the armature 4361drops to its back position. thereupon completed from ground over the front contact and armature 436, the sixth contact of the selecting relay 412, conductor 377, armature 317 and its front contact, front contact and armature 315, front con- A supervisory circuit is' tact and armature 312, the supervisory con ductor 289, armature 295 and its front contact, armature 252 and its front contact, front contact and armature 248, conductor 288, armature 174 and its back contact,.and winding of therelay 156 and battery to ground.

It will be noted that, upon the energizaa tion 01 each selecting relay, a circuit is pre pared for the relay 158 from ground through battery, winding oi the relay 153, the seventh contact of the selectin relay 161. and

throughthe winding of the relay 212 to battery and ground.

The energization'of the relay 212 operates the armature 217 to unlatch the armature 218 which now drops to its back position, opening the energizing circuit of the lamp 135 and completing an energizing circuit for the lamp 138.

The lamp 135, when illuminated, had.

heretofore indicated the circuit breaker to be in a tripped position, and the illumination of the lamp 138 now indicates the circuit breaker to be in a closed position.

A further result of the cnergization of relay 212 is to complete an energizing circuit for relay 158 over the circuit traced above. The next supervisory signal is therefore transmitted to relay 157.

In a similar manner, the dispatcher may trip the circuit breaker by rotating the key to its present shown position and again closing the master key 206. An impulse would thereupon be transmitted from the negative side of battery at the master key 206 through the contacts of relay 427 which, upon energization of relay 429, completes acircuit for the tripping solenoid 433.

Should a circuit breaker automatically opcrate, the normally closed holding circuit would be opened and the selectors would be set into operation 1n substantially the same manner as that already described in detail in connection with the closing of the start key.

For tie purpose of illustration, it will be assumed that the circuit breaker 431, shown in its tripped position, is operated to its closed position. The energizing circuits for the relays 426 and 425 are simultaneously opened at the pallet switch 434. The relay 426, being a fast relay, and relay 425 being a slow relay, the former will permit its armature to drop to its back position before the latter releases its armature. A momentary circuit will, therefore, he completed from ground over armature 441 and its back contact, front contact and armature 437, the conductor 372, front contact and armature 349, through the winding ofthe relay 334 tohatt'ery and ground. It will be recalled, of course, that, with the apparatus in its normal iron-operatingposition, a circuit was completed fort-he holding relay 335 which was described in detail hereinabove.

' The energization of the relay 334 completes an energizing circuit for the relay 301 from ground through battery, winding of the relay 301, front contact and armature 346, armature 347 and'its front contact, back contact and armature 359, and back contact and armature 361 to ground.

A locking circuit is also completed for the relay 334 over this circuit. The energiza'tion of the relay 301 opens. thenormal holding circuit for they relay 335 at armature 3l2-and simultaneously switches the control and supervisory lines to their operating positions.

The energizationof the relay 301, in'opening the original holding circuit, also de-enei: gizes the relay 224'. From this point, the operations are exactly the same as those already described in detailhereinabove, each apparatus unit being connected to the si gnalling line simultaneously with the connection of its individual equipment to the signalling line at the office and a supervisory signal indicative of the condition of the unit is thereupon transmitted.

One of the chief features of the invention resides in the check circuit which operates following theenergization of the selecting relay at each end. This check circuit may be made individual to a large number of selecting relays by employing all of the signalling lines connecting the stations and two polarities.

In the case of the first selecting relay, the check, circuit,; it will be. recalled, is completed from ground at the oflice over the conductor 290 tobattery at the substation.

The check circuit for the second selecting relay is completed from battery at the oflice through the fourth contact of the selecting relay and over the line 290 to ground over the second contact of the selecting relay at the substation, This check circuit is completed from ground through battery,

through the winding of the relay 265, the

armature 282 and its back contact, conductor 192 the fourth contact of the selecting relay 162, conductor 195 through the back contact and armature 283, switch 214, in its closed position, winding of the relay 263, armature 247 and its back contact, back contact and armature 253, front contact and armature 255, conductor 290, armature 311 and its front contact, armature 314 and its back contact, the back contact and armature 321 to the winding of the relay 305, CODCCJCCOZ 379, armature 471 and its back contact and the fourth contact of the selecting relay 413 to ground. The check circuits for the third and fourth selecting rela s are completed from ground at the oflice to battery at the substation over the line 289 and from battery at the office to ground at the substation over the line 289, respectively. These circuits are identical with the first and second checking circuits tracer in detail above, with the exception that, since relay 226, energized upon the energization of the third selecting relay, the check circuit, which formerly was completed over armature 247 and its back contact, is now completed over armature 247 and its front contact and at the substation, since the relay 304 is energized following the energization of the 3rd. selecting relay for completing the check eircuit'over the front contact of armature 321. it will be noted that the fourth contact of the selecting relay 163 is connected in multiple with relay 161 to ground. As will be recalled, the check circuit is completed over this fourth contact. Similarly, the fourth contact of selecting relay 164, it will be noted, is connected to in multiple with the fourth contact of the selecting relay 162. Accordingly, the third and fourth check circuits are identical with the first and second, respectively, except for the signalling line over which it is transmitted.

By periodically changing the character of the drive impulses, a large number of selecting relays may be energized before the same combination of drive and check circuit is repeated. In other words, a synchronous relay system is provider in which the relays are energized synchronously by means of an individual code for each point.

The arrangement for switching the drive circuit so as to change its character is disclosed by the relays 220 to 222. In this particular instance, four drive impulses of the same character are transmitted while each of the checking impulses are changed either by a change of polarity or a change of conductor. Upon the energization of the third selecting relay and in starting the fourth cycle of operations for energizing the fourth selecting relay 164, an ener izing circuit is completed for the relay 221 from ground through battery, Winding of the relay 221, the contact 232, conductor 187, back contact and armature 119, front contact and armature 116, front contact and armature 114, front contact and armature 112, conductor 189, back contact and armature 267, and front contact and armature 272 to ground.

This circuit, it will be noted, is in multiple with the energizing circuit for selecting relay 164.

The energization of the relay 221 operates its armature 233 which is a make-beforebreak contact, and the relay 221 completes an energizing circuit for itself, from ground through battery Winding of relay 221, front contact and armature 233 and the front contact and armature 239 to ground.

An energizing circuit is therefore completed for the winding of relay 222 from ground through battery, the Winding of the relay 222, the contact 235, armature 234 and its front contact, and back contact and armature 272 to ground.

The energization of the relay 222 operates a make-before-break contact at armature 236 and completes a locking circuit for itself thereupon from ground through battery, winding of relay 222, front contact and armature 236, and the front contact and armature 239 to ground.

It Will be recalled that the drive circuit heretofore traced was completed from ground through battery, back contact and armature 238, armature 240 and its front contact to the Winding of the drive relay 258. As the drive circuit was periodically opened and closed by the energization and de-energization of the relay 260, as has been described in detail, an impulse of the same polarity was transmitted over the drive line.

pen the energization of the relay 222, as described above, the drive relay 258 is now connected to ground at the oflice over armature 238 and its front contact.

At the substation, upon the energization of the third selecting relay and its switchover relay and at the beginnin of the fourth cycle of operations, an energizing circuit is completed for the relay 308 from ground through battery, the winding of the relay 308, the contact 331, conductor 371, the back contact and armature 454, the front contact and armature 451, front contact and armature 449, front contact and armature 447, conductor 367, the back contact and armature 354 and front contact and armature 350 to ground. This circuit is in multiple with the energizing circuit for the fourth selecting relay 415.

The energization of the relay 308 completes a locking circuit for itself from ground through battery, Winding of the re lay 308, front contact and armature 329, and the front contact and armature 324 to ground, and the armature 330 prepares an energizing circuit for the relay 307. At the end of the fourth cycle, the drive relay 336 is de-energized as described above, and an energizing circuit is thereupon completed for the relay 307 from ground through battery, winding of the relay 307, contact 390, the armature 330 and its front contact, and

the back contact and armature 350 to ground. l

The relay 307, upon energization, locks it self over the front contact and armature 327 I and the front contact and armature 324. j It will be recalled that the drive circuit was completed from ground over armature 328 at the substation and through the winding of the drive relay 336 to the drive line 291. Upon the energization of the relay. 307, the drive relay at the substation is connected to the battery and, as has been described in detail above, the drive relay at the ofiice now connected to ground.

T he next four impulses will now be transmitt-ed with this reversed polarity of impulses over therdrive line, while the first four check impulses in this particular illustration will repeat themselves. When the seventh selecting relay has been energized and the eighth cycle of operation commences, a circuit is completed in multiple with that of the selecting relay 168 for en-.'

ergizing the relay 220 from ground through battery, Winding of the relay 220, conductor 186, back contact and armature 129, front contacts of the armatures 126, 124, 122, 119, 116, 114 and 112 over, the conductor 189,

the back contact and armature 267 and the front contact and armature 272. to ground. Relay 220 locks itself over armatures 231 and 219.

Upon the de-energization of the relay-258,"

the energized relay 220 shunts the windings of the relay 220t0 222 at armature 230 and its front contact. The relays 220 and 222 are thereupon de-energized and restored to their normal positions. The driving impulse for the ninth and tenth selecting relays is thereupon completed ,in a similar manner to that described in connection with the first two selecting relays.

At the substation end, upon the energization of the seventh selecting relay and at the beginning of the eighth cycle,an energizing circuit is completed for the relay 309 from ground through battery, winding of the relay 309, conductor 369, back contact and armature 464 and the front contact of armature-s 461, 459, 457, 454, 451, 449 and 447, conductor 367, back contact and armature 354 and the front contact and armature 350 to ground. The relay 309 looks over armatures 333 and 390. The energization of the relay 309 prepares a shunt circuit for itself and the Winding of relays 307 and 308 at armature 332. At the end of the eighth selecting cycle the armature 350, the drive relay 336 drops to its back contact, and the battery for energizing these three relays is shunted through the front contact of armature 332 to the back contact of armature 350 to ground. The relays 307 to 309 are thereby de-energized and dropped to their 7 back position. As already pointed out, the

armature 272 to ground.

drive impulse forthe ninth and tenth select ing relays is similar to that for the first selecting relay.

Change in polarity of the check relay circuit is accomplished by grounding the fourth contact of each alternate odd nunir bered selecting relay at the oilice while connecting a batterythrough winding of relay 265 to the fourth contact of each'alternate even-numbered selecting relay at'the office.

Similarly, round is connected to the fourth contact of each of the alternate oddnumbered selecting relays at the substation, while battery is connected throughlthe Wind'- ing of the relay 422 to the fourth contact of each alternate even-numbered selecting relayat the substation. I

In this manner, the check circuit of the first selectingrelay at each station is completed from ground at the office to battery at the substation while the check circuit for.

the second selecting relay is completed from batteryat the office to, ground at the substation. The change of the conductor over which thecheck circuit is to be transmitted is controlled by the relay 226 at the office and the relay 304 at the substation. v

This change occurs for thefirst time at the beginning of the third selecting operation. At the end of the second selecting operation and the beginning of the third cycle of operations, a circuit is completed for the relay 226 from ground through battery, winding of the relay 226 contact 245, conductor 188, armature 117 and its front contact, armature 120 and its back contact, back contact and armature 119, and the front contact of armatures 116, 114, and 112 over the conductor 189, back contact and armature 267 and the; front contact and This circuit, it will be noted, is completed in multiple with the energization of the third selecting relay. The energization of the relay 226 completes a locking circuit for itself from ground through battery, through the winding of relay 226, front contact and armature .246 and the front contact and armature 273 to ground.

The check circuit, it will be -recalled, was originally traced over armature 247 and its back contact, back contact and armature 253, and the frontcontact and armature 255 over the control conductor 290. v This check circuit, upon the energizatien of the relay 226, is now completed over armature 247 and its front contact, back contact and armaback contact of armature 452, back contact of armature 451 and the front contact of armatures 449 and 447, conductor 367, back contact and armature 354 and the front contact and armature to ground.

The energization of the relay 304 operates its armature 321 to its front contact. It will be recalled that the check circuit at the substation was traced from the control conductor 290 over armature 311 and its front contact, armature 314 and its back contact, and the back contact and armature 321.

The check circuit will now be traced from the supervisory conductor 289 over the armature 312 and its front contact, armature 315 and its back contact and the front contact and armature 321. In this manner, the check circuit is transmitted over a different line for the third and fourth selecting relays. The relay 304, it will be noted, is again energized at the beginning of the fourth cycle over armature 452 and its front contact, and armature 455 and its back contact, over armature 454 and its back contact, and the front contact of arniatures 451, 449 and 447 to ground over the conductor 367.

Similarly, the check circuit is reversed at the fifth and sixth selecting relays over simi lar circuits. If the apparatus, for any reason, falls out of step and the third selecting relay at one end energizes simultaneously with the fourth selecting relay at the remote end, the check circuit, as has already been described in detail, will fail to operate since it depends for its completion upon the energization of the proper selecting relays.

Should the check circuit fail to operate, an energizing circuit is completed for the relay 264 from ground through battery, the

' winding of the relay 264, conductor 191,

through the fifth contact of the selecting relay energized, conductor 196, back contact and armature 251, back contact and armature 281, back contact and armature 285,

and the front contact and armature 273 to ground.

7 An energizing circuit for the relay 264, it will be noted, is completed over the arma ture back contact 281 of the check relay 263 and, therefore, would not have been completed had the checking circuit correctly operated.

Upon the energization of the relay 264,

the checking circuit is opened at armature 283, thereby preventing operation of the A circuit is also completedcheck circuit. for the relay 261 from ground through battery, armature 250 and its back contact, through the Winding of the relay 261, the

front contact and armature 269, back contact and armature 271, back contact and armature 251, back contact and armature 281, back contact and armature 285 and the front contact and armature 273 to ground. It will be noted that this circuit is completed over the back contact of the checking relay 263 and would, therefore, not have been completed had the checking circuit properly operated.

The energization of the relay 261 func tions to restore the selecting apparatus to normal by completing an energizing circuit for the restoring relay 160 from ground over armature 277 and its front contact, conductor 199 and through the winding of relay 160 to battery and ground.

The energization of the relay 160 prepares an energizing circuit for the relay 159 at armature 178, and, at armature 177, completes a locking circuit for itself from ground through battery, winding of the relay 160, armature 176 and its back contact, front contact and armature 177 and the back contact of armature 175 to ground. At the same time, ground is removed from the conductor 198.

It will be recalled that the relays 225 and 229 have been held energized over ground found on conductor 198. The relays 225 and 229 therefore immediately de-energizc upon removal of ground from conductor 198. The de-energization of the relay 229 opens the energizing circuit for the relay 223. The de-energization of the relay 223 opens the locking circuit for all the switch over relays'101 to 110 at armature 239. and those of the relays which have been energized and locked are now restored to normal.

The lamp 205 which, when illuminated, indicates the set in operation is now extinguished and the lamp 202 indicating a normal non-operating condition is illuminated. The normal holding circuit for the relay 224 is prepared at armature 239 and 295.

The energizing circuit for the drive relay 258 is opened at armature 240, and the drive relay drops to its back position, restoring whatever relays have been pulled up, in a manner already described.

The de-energization of the relay 258 completes an energizing circuit for the relay 159 from ground over armature 273 and its back contact, armature 271 and its back contact, armature 269 and its back contact, over the conductor 287, the armature 178 and its front contact, through the windings of the relay 159 and battery to ground.

The energization of the relay 159 opens the locking circuit of the restoring relay 160 at armatures 175 and 176 which, upon de-energization, in turn, opens the energizing circuit of the relay 159 at armature 178.

The above described operations, it will be noted, occur originally when the drive relay 258 is in an energized condition. A nonsynchronous condition can occur only following some operation. The circuits are so arran ed that operations take place only during the period that the drive, line is armature 310.

closed. It is obvious, therefore, that anonsynchronous condition wlll occur When the relay which happens to be up atthe time, over the conductor 376, backcontact and armature 313, back contact and armature 322, over the conductor 380, back contact and armature 473, conductor 381 front contact and armature 351 to'ground.

The energization of the relay 423ropens the check circuit at armature 471, thereby preventing the check relay from' operating. Simultaneously, a multiple circuit is completed for the restoring relay 339 from ground through the battery, armature 318 and its back contact, through the winding of the relay 339, front contact and armature 355, front contact and armature 353, back contact and armature 313, back contact and armature 322, conductor 380, back contact and armature 473, conductor 381 and the front contact and armature 351 to ground.

The energization of the relay 339 functions to restore the selecting apparatus at the substation in the following manner. An energizing circuit is completed for the relay 340 from ground over the armature 357 and its front contact, and through the wind-- ing of relay 340 to battery and ground. The relay 340 locks itself over the armature and back contact of 360, armature and make contact 359 and back contact and armature 361 to ground. p 1 I The energizaticn of the relay340 prepares an energizing circuit for the relay 341 at armature 358 but this circuit is not completed at this time because the circuit is opened at the armature 355 which is, at this time, on its front contact.

A further result of the cnergization of the relay 340 is to put ground on the conductor 373 from ground over armature 361 audits front contact, armature 359 and its front contact, back contact and armature 360, over the conductor 373, and to remove ground from the circuits of the relays 301 and 334.

The cnergization of the relay 340 restores the control and supervisory lines to their normal non-operating positions preparing the holding circuit originally traced at armature 312 and its front contact and opening the energizing The de-energization of the relay 306 removes ground from the conductor 366 and opens the drive line. The removal of ground from the conductor 366 restores all the switch over relays 401 to 410 which have been locked over their conductor 366- circuit of the relay 306 at;

The de-energization of the switchover relays opens the energizing circuits of the relays 337 and 338, and the opening of the driveline de -energizes the drive relay 336. As the drive relay is de-energized and the relays 337 and 333 are de energized, an energizing circuit for the relay 341 is completed from ground through battery, the winding of relay 341, front contact and armature 358, back contact and armature 355, back contact and armature 353 and back contact and armature 351 to ground.

The relay 341, upon energization, opens the locking circuit for the relay 340 at armatnres 360 and 361, and the relay 340 is deenergized to in turn open the energizing circuit of the relay 341 at armature 358. In this manner, the apparatus at the substation is automatically restored to'normal upon a non-synchronous condition. I

If, for any reason, two selecting relays at the ofiice should be pulled up simultaneously, arrangements are provided for preventing any false operation.

7 It will be assumed, for illustration, that the relays 161 and 162 are pulled up simultaneously. A circuit is thereupon completed for the relay 265 from ground through battery, winding of the relay 265,armature 282 and its back contact, conductor'192 through the fourth contact of the relay 162 and the fourth contact of the relay 161 to ground.

The relay 265,upon energization, conipletes an obvious energizing circuit for the completed for the relay 422 from ground through battery, the Winding of the relay 422, armature 472 and its back contact,

throughthe fourth contact of the relay 420, the fourth contact of relay 421 to ground.

' The energization of relay 422 completes an obvious energizing circuit for the relay 23 at armature 474. The energization of the relay 423 opens a circuit of the checking relay 305 at the substation, thereby preventing the checking relay from operating causing the restoring relays 340 and 341 to In this manner that has already operate. been described. in great detail, the apparatus 15 restored to normal.

Should a failure occur anywhere in the selection this may be of a temporarynature and one which wouldnot recur. In such a case, itis desirable to permit the dispatcher to restore the apparatus and restart in the hope that-the; trouble will not re-appear.

By the operation of the key 209 in closing its outer contacts, the drive circuit which, it will be recalled, was traced through the closed contacts 210, 215 and 216, is opened. A local circuit is simultaneously closed for the drive relay 258 from ground over the back contact and armature 237, the left-hand contact 210 through the winding of the relay 258, the closed contact 219 and the back contact and armature 238 to battery and ground.

The energization of the drive relay 258 at the oilice starts the cycle of operations for a regular selection, in a manner which has been described hereinbefore. However, when a checking circuit is to be operated, it will obviously fail since no circuit can be completed for it, and, as a result, the restoring relay 261 Will be energized to restore the apparatus to its original normal non-operating position.

A multiple circuit for the drive relay at the substation is, at this time, also completed from ground through battery, back contact and armature 238, right-hand contact at 215, contact 216 and over the drive line 291 through the winding of the relay 336, front contact and armature 325 and armature 328 to ground.

The drive relay at the substation energizes and starts the cycle of operations which has already been described in detail but the checking circuit fails to operate and the apparatus, is restored to normal.

If the polarity in the drive line has been reversed, that is, the relay 222 at the office and 307 atthe substation have been energized, the circuit for the drive relay 258 is closed over the contacts of the key 209 in exactly the same manner as has already been described except that the circuit Will be completed from ground over the front contact of armature 238, through the winding of the relay 258 and through the key 209 to the front contact of armature 237 and battery to ground instead of the circuit traced above.

By manipulating the key 213 to close its right-hand contact, ground is placed upon the drive relay 336. At the substation, this relay is connected to battery, and the relay functions as already stated.

The apparatus thus may be restored to normal at any point in the selecting operation, the restoring being performed at will and under the control of the dispatcher. This makes it possible to operate an ex ceedingly large system since it is not necessary to always go through the entire chain of relays if the unit to be selected is near the beginning of the chain.

Thus, if the unit is the second in the selectin g chain it is only necessary to go to the third point at which position operation of the key 209 enables the dispatcher to restore it to normal.

Although I have disclosed my invention in connection with a supervisory control system, it is obvious that the system for synchronously operating the relays has application to many other forms of electrical systems and I do not intend to limit myself by the specific form disclosed except insofar as limited by the appended claims.

I claim as my invention:

1. In a supervisory control system, a first station, a second station, a chain of sel cting relays at each of said stations, apparatus units at said second station, one for each relay, a drive line connecting said stations, a control and supervisory line connecting said stations, means for transmitting impulses over said drive line, means responsive to an impulse over said drive line for energizing equivalent selecting relays simultaneously at each of said stations, means responsive to the energization of said equivalent selecting relays for transmitting an impulse'over either said control or supervisory line of either polarity in accordance With the particular selecting relay energized, means rcsponsive to said impulse for connecting said control or supervisory line to operating position including contacts of said selecting relay, and means including said control and supervisory line and the contacts of said selecting relay for selectively operatingand supervising said remotely disposed apparatus unit from said first station.

2. In a signalling system, a first station, a second station, distributors at each of said stations, a drive line connecting said stations, means for operating said distributors in synchronism, said means including said drive line, a second line connecting saidstations, means including said second line and responsive to the synchronous operation of said distributors for transmitting impulses thereover, means responsive to the impulses for switching said second line to an alternate position, apparatus unit at said second station, and means including said second line in its switched position and said distributors for selectively operating said apparatus unit from said first station.

3. In a signalling system, a station, a chain of selecting relays at the station, a switch-over relay individual to each of said selecting relays, a signalling line, extending to said station, means for transmitting an impulse over said signalling line, means re sponsive to said impulse for operating one of the selecting relays, means responsive to the energization of said selecting relay for rendering said impulse-responsive means non-operative to energize a selecting relay, means including circuit connections for simultaneously energizing the individual switch-over relay, means for terminating 

